Optically pure amino acids are used as a ligand of asymmetric catalysts, or may be widely utilized as starting materials or intermediates necessary to synthesize a variety of medical products and physiologically active materials, and are thus regarded as a very important compound from the industrial point of view [Helmchen, G.; Pfaltz, A., Acc. Chem. Res. 2000, 33, 336-345].
It has been known that amino acids are economically produced via fermentation. However, amino acids resulting from fermentation are limited to only L-amino acids among natural amino acids. Although optically pure D-amino acids and non-natural amino acids are produced via an enzyme process or an optical resolution process, they cost a lot to prepare and thus their unit prices are about 5 times to 10 times higher than those of natural L-amino acids resulting from fermentation as well as their mass production is difficult to achieve. Therefore, there have been efforts to achieve economical mass-production of amino acids [Maruoka, K.; Ooi, T. Chem. Rev. 2003, 103, 3013].
As a part of the efforts, the present inventors have developed a method of transforming L-amino acid into D-amino acid by recognizing chirality of aminoalcohol and amino acid via an imine bond using a binaphthol derivative having an aldehyde group as represented by the following chemical formula [(a) Park, H.; Kim, K. M.; Lee, A.; Ham, S.; Nam, W.; Chin, J., J. Am. Chem. Soc. 2007, 129, 1518-1519; (b) Kim, K. M.; Park, H.; Kim, H.; Chin, J.; Nam, W., Org. Lett. 2005, 7, 3525-3527].

Meanwhile, an enantioselective liquid-liquid extraction (ELLE) process is a simple process and easy to scale up and also enables the production of amino acids at low costs. Thus, the production of optically pure amino acids by the ELLE process has been studied for a long time [Schuur, B.; Verkuijl, B. J. V.; Minnaard, A. J.; de Vries, J. G.; Heeres, H. J.; Feringa, B. L. Org., Biomol. Chem. 2011, 9, 36-51]. A very important factor in ELLE of amino acids is the development of a chiral extracting agent with a high selectivity. Numerous chiral extracting agents for amino acids have been developed so far, but they have a selectivity of from about 2/1 to about 5/1. Therefore, it is desperate to develop a chiral extracting agent having a high selectivity to perform the ELLE of amino acids [(a) Amato, M. E.; Ballistreri, F. P.; D'Agata, S.; Pappalardo, A.; Tomaselli, G. A.; Toscano, R. M.; Sfrazzetto, G. T. Eur. J., Org. Chem. 2011, 28, 5674-5680; (b) Colera, M.; Costero, A. M.; Gavina, P.; Gil, S., Tetrahedron: Asymmetry 2005, 16, 2673-2679].
Recently, the present inventors filed a patent application relating to a method of using a binaphthol derivative which is described above as a chiral converting agent for amino acids, as a chiral extracting agent for the ELLE of amino acids (Korean Patent Application No. 10-2009-0032956). This binaphthol derivative enables the extraction of amino acids from an aqueous solution layer to an organic layer by forming an imine and has a chiral selectivity of from about 5/1 to about 20/1 depending on the kind of an amino acid, and the chiral selectivity is higher than those of previously developed chiral extracting agents.
The present disclosure was achieved in the development of a chiral extracting agent having a remarkably higher chiral selectivity than this previous binaphthol derivative.